January 3, 2019
Farmers across the Midwest dealt with stalk integrity issues last fall. Stalk and crown rots caused by a combination of stressful environments cannibalized stalks and many fields had down corn. In places where corn was down and ears were not picked up very well, volunteer corn may be an issue this spring (Figure 1). Volunteer corn can compete with the next crop for light, moisture and nutrients, and can cause yield loss regardless of crop. Volunteer corn can also be a harbor for corn rootworm and some foliar corn diseases. By allowing these insects and diseases to thrive in the volunteer corn, the effects of a crop rotation can be minimized.
Figure 1. Volunteer corn plants growing from overwintering ear.
The first step to managing volunteer corn is prevention. Factors that can aid in prevention include:
- Products with strong roots and stalks to help minimize lodging.
- Products with known ear shank issues should not be planted to help minimize ear drop.
- Products with weak or lodged stalks should be harvested first.
- A properly adjusted combine to help minimize kernel loss out of the back of the combine. Those kernels can overwinter, germinate in the spring and become volunteer corn plants.
If it is known that volunteer corn is going to be an issue, no-tilling next year’s crop can help minimize the opportunity for corn kernels to achieve good seed to soil contact and germinate. In a conventional tillage system, it may be a better idea to till in the fall to encourage germination of lost corn seed before a killing frost. A good management practice is to plant soybean instead of corn where volunteer corn plant numbers are expected to be high because there are more herbicide options for killing corn in soybean (Table 1).
Many farmers choose to control volunteer corn midseason instead of early season because they want to allow most of the potential volunteer corn plants to emerge. In corn-on-corn fields where volunteer corn pressure can be high, consider herbicide management of the volunteer corn pre-plant due to limited options in-crop. Growers may also not realize they can have an issue during the timing of the first herbicide application of the season. Allowing the volunteer corn to grow longer can cost some yield potential. Also, by allowing a volunteer corn plant to increase in height from 6 to 12 inches to 12 to 24 inches requires more herbicide for control which would increase management cost.
As mentioned in the opening paragraph, by controlling volunteer corn, the pests and disease cycles that come along with volunteer corn can be broken up. The longer the volunteer corn is left to stand in the field, the longer the environment is there for pests and diseases to move in and keep the cycle intact.
Managing volunteer corn in continuous corn environments can be a bit tricky. There are several products on the market that can kill volunteer corn but have longer plant-back restrictions. See Table 2 for the most effective methods of killing volunteer corn in a continuous corn system. Additionally, please visit RoundupReadyPLUS.com for more information on managing volunteer corn plants.
Sources:
Jhala, A., Wright, B., and Chahal, P. Volunteer corn in soybean: Impact and management. https://cropwatch.unl.edu
Additional Source: Managing volunteer corn in your soybean and corn fields. Agronomy ADVICE. Channel.com. http://www.channel.com/agronomics/Documents/AgronomicContentPDF/ManagingVolunteerCorninYourSoybeanandCornFieldsChanneAdvicel.pdf